Reinforced steel plate



R- A NELSON,

Patented Oct. 19, 1920.4

UNITED STATES PATENT OFFICE.

ROY .ARTHUR NELSON, OF CHICAGO, ILLINOIS.

REINFORCED STEEL PLATE.

Specification of Letters Patent.

Patented Oct. 19, 1920.

To all whom it may concern.:

Be it known that I, ROY A. NELSON, a citizen of the United States, residing at Chicago, in the County of Cook and State of Illinois, have invented a certain new and useful Improvement in Reinforced Steel IPlates, of which the following is a specification. l

My invention has for its object to improve the construction described' in my copending application, Serial `No. 316,539, iiled August 11', 1919, in which I provided for a central circular corrugation in the plate with radiating corrugations extending therefrom, in which thereiwas no crossing or intersection between thev vcorrugations. As described in the saidapplication, the central circular corrugation inclosed an area the surface of which was plane. This surface was liable to buckle orbulge in use, and my present invention hasfor its object to provide a construction which will avoid any such possibility;

My means of accomplishing this object will be more readily understoodv by having reference to the accompanying drawing which is hereunto annexed and is made a part of this specification, in which:

Figure 1 is a front elevation of a car door constructed in accordance with my improvement..

Fig. 2 is an enlarged sectional detail view, taken on the line 2-2 in Fig. 1.

Fig. 3 is a fragmentary sectional View taken on the'line min Fig. 1.

Similar reference numerals refer to similar parts throughout the entire description.

As shown in the drawing, the door is constructed in two parts 4. and 5, which are lapped over and suitably joined by riveting, electric welding or any other suitable means. The plates are then placed in a press and a central endless corrugation 6 is stamped therein. A plurality of corrugations, 7 8, 9, 10, 11, 12, 13, and 14 are stamped in the plates, and radiate from the central corrugation 6, but it is essential that these corrugation'js-lsho'uld not extend their apex to the apexoflthe circular corrugation 6. Within the circular corrugation 6, I provide a plurality of arrow points formed-by-gcorrugating theplane surface within the endless corrugations-6. These points 18 join the inner wall ofthe central or endless corrugation 6, but should be constructed so that their apex does not extend to the apex of the said endless corrugation. In this manner I avoid weakening the endless corrugation, as practice has shown that where two corrugations cross each other their intersection is their weakest point, and it is at this point that the metal usually fractures and breaks.

The corrugations or arrow heads 18 extend internally and terminate in a point as shown.

It is not necessary to provide corrugations within the endless corrugation 6, for each of the radiating corrugations, unless the endless or circular corrugation 6 is of very great diameter.

Having described my invention what I regard as new and desire to secure by Letters Patent of the United States, is:

1. A metal plate provided with a centrally located circular corrugation, a plurality of corrugations extending from the outer side of the circular corrugation, said corrugations joining the outer surface of the circular corrugation at a point below the, apex of the circular corrugation, a plurality of pointed corrugations located inside of saidcircular corrugation and extending inwardly therefrom, said inner corrugation joining the inner surface of the circular cor rugation at a point below theapex of the circular corrugation.

2. A sheet metal door comprising a plurality of sheet metal plates joined to form one continuous plate, and a circular corrugation formed centrally thereon, a plurality of corrugations radiating therefrom, the inner ends of which join said circular corrugation at a point below its apex, a plurality of inwardly extending corrugations opposite alternate radiating corrugations, said inwardly extending corrugations terminating at a` point adjacent the center, said inwardly extending corrugations joining the inner surface of the circular corrugation at a point below its apex.

3. A sheet metal door comprising a plurality of sheet metal plates joined to form one continuous plate, a circular corrugation` formed centrally thereon, a plurality of corrugations radiating therefrom, the inner ends of which join said circular corrugation at a point below its apex, a plurality of inwardly extending corrugations terminating at a point adjacent the center, said inwardly extending corrugations joining the inner surface of the circular corrugation at a point below its apex.

ROY ARTHUR NELSON. 

